Pressure carburetor



y 6, 1947- G. M. HOLLEY, JR

PRESSURE CARBURETOR Filed Nov. 10, 1943 G EUWMEIIEJebI INVENTOR.

Patented May 6, 1947 PRESSURE CABBURETOB George M. Holley, Jr., Detroit, Mich, assignor to George M. Holley-and Earl Holley Application November 10, 1943, Serial No. 509,944

The object of this invention is to provide a pressure-type carburetor of the simplest possible construction consistent with proper compensation for altitude. load, and temperature. A minor object is to locate the vapor separator immediately before the fuel flows through the metering orifice. I have discovered that if there is any pressure regulating valve located between the metering orifice and the vapor separator, the pressure regulating valve causes a slight separation of the vapor from the fuel, and even a slight separation of vapor from fuel will seriously interfere with accurate metering of the flow of fuel through the fuel orifice.

In the drawing, i is the air entrance. II is the venturi located therein which creates a pressure difference responsive to the airflow, which pressure difference is applied to the bellows i2 through the pipes l3 and I4. Throttle l5 controls the airflow. Below the throttle Hi, the fuel discharge outlet I3 is located in which there is a valve I! which is seated by a spring and opened by fuel pressure. The fuel enters the carburetor at I3 and enters the chamber IS in which is located a float 20 which controls the vapor separator valve 2| which allows the air or vapor to escape through the pipe 22 which discharges on the atmospheric side of the throttle Iii. The fuel passes from the chamber l9 down the pipe 23 past the control valve 24 through the passage 25 into the chamber 23; Chamber 21 is separated from the chamber 26 by a diaphragm 28. Chamber 21 communicates with chamber l3 by the passage 29, which passage 29 is a helical passage to prevent surging. The diaphragm 28 supports the balanced valve 30. The diaphragm 28 is supported by the compression spring 3|. The effect of pressure in the passag 25 is to close the valve 30. The tendency of the spring 3| is to open the valve 30 admitting fuel down the passage 32. The passage 32 communicates with the pipe 33 which is connected to the fuel outlet nozzle IS. The pressure responsive element i2 is coupled to the 1 Claim. (Cl. 281-41) barometric responsive element 34 and the two are the diaphragm 43, supported by the compression spring 44, fuel being supplied from the passage 23 through the bypass passage 4! controlled by the valve 42. A pipe 46 subjects the diaphragm 43 to a suction below the throttle when the throttle' i5 is in the idle position. When the throttle It opens, substantially atmospheric pressure is restored to pipe 46 and the diaphragm 43 immediately thereafter closes the valve 42 and idle fuel is no longer supplied.

Operation Assume that the engine is running with the throttle it slightly open. There is then a great suction adjacent to the downstream side of the downstream lip of the throttle II. This causes a. high suction in'the pipe 43 which causes the diaphragm 43 to move to the left, compressing the spring 44 and admitting a little fuel from the inlet l8, bypassing the valve 24 and flowing into the chamber 26, moving the diaphragm 23 to the right and letting fuel flow out past the valve 3| down the passage 32, past the valve l1 and th discharging through the nozzle l3.

When the throttle i5 is moved far enough so as to place the passage 46 on the atmospheric side of the downstream lip of the throttle ll, atmospheric pressure is transmitted through thepassage 46 to the left-hand side of the diaphragm 43 causing the diaphragm 43 to move to the right under the influence of the spring 44 causing the needle 42 to close the bypass 45 and from there on, the fuel is controlled solely by the. double tapered valve 24. The control of this valve is in response to the depression in the throat of the venturi l I. This depression is transmitted to the chamber I2 which moves the rod 38 to the right.

When the pressure becomes great enough as when at sea level, the element 34 is compressed and-the valve 24 is moved to the right so that when the plane is flying in the extremely dense air which is found close to the earth's surface. it compensates for this abnormal condition. The dense air compresses the element 34 and thus opens the valve 24. The valve 24 is shown with double taper to make the mixture suiiiciently rich to prevent the. engine from over-heating. When running the engine there is a steady flow of air into the end of the chamber 33 up the pipe and down the pipe 41 so that th air at atmospheric temperature is below that of the element 34 which contains a small quantity ofair; hence 34 responds to both temperature and pressure. When the temperature gets high or the barometer gets low, the rod 38 moves to the left so as to restrict the flow of fuel through passage 35. The functionofth'evapor separator 2 i22 is no part of this "the average pressure of the pressure in chamber II.

The pressure difference between the chamber l9 and the chamber 23 is maintained by the spring 3i and the valve III carried by the diaphragm 28. Variation in pressure in chamber II will not appreciably influence the mixture ratio.

What I claim is:

In a carburetor of the pressure type, a source of fuel under pressure, a pressure regulating control valve adapted to control the admission of the fuel to the engine, a moving wall controlling said valve, a passage connecting the two sides of said wall, a fuel flow controlling restriction in said passage, a portion 'of said passage connecting the chamber 011 one side of the moving wall with the entering fuel under pressure, the other side of the wall being subjected to the pressure on the downstream side of said restriction, a metering valve in said restriction, a venturi in the air entrance to the engine, means responsive to the depression in the throat of said venturi adapted to open said metering valve, a butterfly throttle, a low- 4 speed fuel control device associated therewith comprising a bypass around said fuel metering restriction, a, valve adapted to control the flow through said bypass, yielding means adapted to close said valve, an air chamber having a moving wall, a passage connecting said air chamber to the air inlet on the downstream side of and adjacent to the downstream lip of said butterfly throttle, said second moving wall being connected to said bypass valve so that the engine suction is adapted to open the valve of the low speed fuel control device when the throttle is almost closed and when the throttle is opened past the idling position, the valve for the low, speed fuel control device is closed.

GEORGE M. HOLLEY. J a.

REFERENCES CITED The following references are of record in the file of this patent:

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